Study: Sea Levels Won't Rise As Much As Predicted

While the disintegrating Columbia Glacier in Alaska is adding to ocean levels, the total global sea rise by 2100 may be lower than some are anticipating, according to a new study.
Tad Pfeffer/University of Colorado
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Tad Pfeffer/University of Colorado

While the disintegrating Columbia Glacier in Alaska is adding to ocean levels, the total global sea rise by 2100 may be lower than some are anticipating, according to a new study.

Tad Pfeffer/University of Colorado

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Sea levels could rise between 2.5 and 6 feet this century as a result of global warming, a new study in the journal Science reports. That estimate is lower than some widely circulated figures, but still represents a serious threat to people who live near the coast.

Tad Pfeffer at the University of Colorado decided to do the study after hearing colleagues predict high rates of sea level rise, without backing the predictions with any solid science.

It's widely agreed that melting ice and expanding seawater could increase sea level by a foot or two this century. But levels can also rise as glaciers in Greenland and Antarctica flow into the sea and break up into icebergs. Scientists have had trouble trying to figure out the size of that effect.

Pfeffer and his colleagues looked for the highest ice-flow rates ever recorded and then assumed, as a worst case, that those would apply to glaciers in Greenland and Antarctica.

In their worst-case scenario, the researchers found, global sea level could rise by between 2.5 feet and 6 feet this century.

The new figure is lower than some guesstimates that seemed to be taking root, but Pfeffer says it's important to have a realistic number.

"A policymaker who's trying to plan for 2 to 4 meters [6.5 to 13 feet] of sea level rise is going to make a very different set of decisions than someone who's trying to plan for 80 centimeters to 2 meters [2.6 to 6.5 feet] of sea level rise," he says.

Still, sea level rise in that lower range could have serious consequences for many millions of people who live near the coast. And sea levels will continue to rise for many centuries beyond 2100, so those higher numbers could eventually become reality.